LAUSR

Background Paranoid thinking is a psychological phenomenon affecting a considerable part of the general population. According to Freeman and colleagues (2005) there is a “hierarchy of paranoia”, which ranks from social worries and beliefs of persecution to paranoid delusions which are common in schizophrenic disorders. Therefore, the assumption of this continual approach leads to the hypothesis that subclinical paranoid thinking and persecutory delusions in context of schizophrenia share a common genetic basis. Our primary aim was to verify this hypothesis. Methods Associations of 128 genome--wide significant schizophrenia risk variants (Schizophrenia Working Group of the Psychiatric Genomics Consortium, 2014) were investigated on paranoid thinking. Individual paranoid thinking was measured with a newly composed subscale based on the Minnesota Multiphasic Personality Inventory (MMPI), in a German sample including 2635 healthy subjects. From this sample n=1174 individuals with either none (n=558) or high (n=616) scores of paranoid thinking were selected. Results Using a logistic regression model controlling for age, sex and education, six markers showed significant associations to paranoid thinking. Interestingly, these associations could indeed be shown in a comparison of extreme groups, but only very restricted in the following variance analysis of continual associations. Discussion Despite discrepant findings, this study suggests a genetic contribution to the complex development of paranoid thoughts.